Coated articles are known in the art for use in window applications such as insulating glass (IG) window units, vehicle windows, and/or the like. It is known that in certain instances, it is desirable to heat treat (e.g., thermally temper, heat bend and/or heat strengthen) such coated articles for purposes of tempering, bending, or the like in certain example instances.
In certain situations, designers of coated articles often strive for a combination of good selectivity, desirable visible transmission, low emissivity (or emittance), and low sheet resistance (Rs). Low-emissivity (low-E) and low sheet resistance characteristics permit such coated articles to block significant amounts of IR radiation so as to reduce for example undesirable heating of vehicle or building interiors.
Coated articles oftentimes are located in harsh environments such as, for example, severe cold, extreme heat and/or humidity, etc. Low-E coatings oftentimes include silver-based layers, and these silver-based layers are subject to corrosion or other forms of damage when located in harsh environments.
It is known to use dielectric thin film layers including materials such as, for example, zirconium oxide, silicon nitride, and the like to help protect against environmental conditions. Unfortunately, however, there oftentimes is a challenge to balance durability with desired optical properties (including, for example, visible transmission, reflection, color, etc.).
One common approach is to use bottom-most and upper-most layers in a thin film layer stack for durability purposes. For instance, a bottom-most layer comprising silicon nitride may help reduce the occurrence of sodium migration from the underlying substrate into the layer stack, and an upper-most layer comprising zirconium oxide may help provide scratch resistance. Other dielectric layers above and/or below the silver-based layer oftentimes are used in an effort to achieve the desired optical properties.
While this approach is oftentimes acceptable, those skilled in the art constantly seek more and more durable coatings for use in a wider array of possible environments, e.g., with desired optical properties.
One aspect of certain example embodiments relates to the inventors' discovery that increasing the number of interfaces in a layer stack promotes durability and corrosion resistance. For instance, increasing the number of layers in a dielectric layer stack from two to three or more with the total thickness of the dielectric layers being kept substantially the same has been found to result in superior durability. As one example, corrosion performance increased twofold.
Another aspect of certain example embodiments relates to the combination of three or more dielectrics directly adjacent to one another, with each generally being a metal reacted with oxygen and/or nitrogen, in the form MxR1yR2z where M is the metal and R1 and R2 the reactive gases, and with each layer including, for example: tin oxide (e.g., SnO2 or other suitable stoichiometry), silicon nitride (e.g., Si3N4 or other suitable stoichiometry), titanium oxide (e.g., TiO2 or other suitable stoichiometry), zirconium oxide (e.g., ZrO2 or other suitable stoichiometry), zinc oxide (e.g., ZnO2 or other suitable stoichiometry), zinc aluminum oxide (e.g., ZnAlxOy or other suitable stoichiometry), silicon oxynitride (e.g., SiOxNy), etc. Such layer stacks may include, in order moving away from the substrate, for example: SixNy/TiO2/ZnO2/TiO2/ZnO2; or SnO2/ZnO2/SixNy/ZrO2; or SixNy/TiO2/ZnO2/SnO2/ZnO2. One or more of these layer stacks may be incorporated above and/or below an IR reflecting (e.g., silver-based) layer in certain example embodiments.
In certain example embodiments of this invention, there is provided a heat treatable coated article, comprising a multilayer thin film coating supported by a glass substrate. The coating comprises, in order moving away from the substrate: a first silicon-based layer; a first dielectric layer; a second dielectric layer split by a third dielectric layer so as to form first and second portions of the second dielectric layer; a metallic or substantially metallic infrared (IR) reflecting layer over and directly contacting the second portion of the second dielectric layer; an upper contact layer comprising an oxide of Ni and/or Cr directly over and contacting the IR reflecting layer; a fourth dielectric layer; and a second silicon-based layer. The third dielectric layer comprises either titanium oxide or tin oxide.
In certain example embodiments of this invention, there is provided a method of making a heat treatable coated article comprising a multilayer thin film coating supported by a glass substrate. A first silicon-based layer is disposed on the glass substrate. A first dielectric layer is disposed, directly or indirectly, on the first silicon-based layer. The method further includes starting to dispose a second dielectric layer, directly or indirectly, on the first dielectric layer; interrupting the disposing of the second dielectric layer and disposing a third dielectric layer; and resuming the disposing of the second dielectric layer on the third dielectric layer, such that the interruption and resumption in the disposing of the second dielectric layer results in the formation of first and second portions of the second dielectric layer, with each said portion being substantially homogenous and amorphous. A metallic or substantially metallic infrared (IR) reflecting layer is disposed directly over and contacting the second portion of the second dielectric layer. An upper contact layer comprising an oxide of Ni and/or Cr is disposed directly over and contacting the IR reflecting layer. A fourth dielectric layer is disposed, directly or indirectly, on the upper contact layer. A second silicon-based layer is disposed, directly or indirectly, on the fourth dielectric layer. The third dielectric layer comprises either titanium oxide or tin oxide.
According to certain example embodiments, the first and second silicon-based layers each comprise silicon nitride, the first dielectric layer comprises titanium oxide, the second dielectric layer comprises zinc oxide, the third and fourth dielectric layers each comprise tin oxide, and the IR reflecting layer comprises Ag. In certain of these example embodiments, the second layer is split such that the parts thereof have thicknesses that vary by no more than 5% of one another.
According to certain example embodiments, a fifth dielectric layer is interposed between the fourth dielectric layer and the second silicon-based layer. The first and third dielectric layers each comprise titanium oxide, and the second and fifth dielectric layers each comprise zinc oxide. The two portions of the split second dielectric layer and the fifth dielectric layer each have thicknesses that vary from one another by no more than 5%, and the first and third dielectric layers have thicknesses that vary from one another by no more than 5%. Thicknesses here and elsewhere may be varied, however, based on deposition conditions, desired properties, etc.
According to certain example embodiments, a topcoat comprising zirconium oxide may be provided, e.g., as an outermost layer of the coated article.
According to certain example embodiments, the coated article may be heat treated.
According to certain example embodiments, each layer may be formed via sputtering in a reactive environment of oxygen and/or nitrogen.
The above-described and/or other coated articles may be included in insulating glass (IG) units in certain example embodiments. Certain example embodiments relate to such IG units, and/or methods of making the same.
The features, aspects, advantages, and example embodiments described herein may be combined to realize yet further embodiments.